Associations between a posteriori defined dietary patterns and bone mineral density in adolescents

Dietary pattern analysis may uncover the joint effects of multiple dietary components on bone health, but such research is scarce and targets mostly adults. We quantified prospective associations between dietary patterns and bone mineral density (BMD) in 1,007 adolescents of a cohort born in 1990 and recruited at schools in Porto during the 2003/2004 school year. Forearm BMD was measured using dual-energy X-ray absorptiometry. Participants' dietary patterns were classified Healthier, Dairy products, Fast food and sweets and Lower intake according to previously identified patterns obtained in a larger sample of 1,489 participants using the K-means method. Using dietary patterns at 13 years old as the main exposure, associations were estimated cross-sectionally (with BMD at the age of 13) and prospectively (with annual BMD variation between 13 and 17 years), using linear regression coefficients adjusted for height, weight, energy intake and, in girls, for menarche age. No significant associations between the a posteriori dietary patterns identified and mean BMD at 13 were found. However, among girls, adherence to a pattern characterized by low intake of energy and all food groups was negatively associated with annual BMD variation between 13 and 17 years [adjusted coefficient (95 % CI) -0.451 (-0.827; -0.074) mg center dot cm(-2)center dot year(-1)]. Although results showed that, in girls, adherence to a Lower intake dietary pattern is associated with lower annual BMD variation throughout adolescence, overall, there were no consistent associations between dietary patterns and forearm BMD in adolescents.